Touch technology can be divided into the following types: resistive, capacitive, surface acoustic wave, optics, etc according to the sensing principles thereof. With the convenience of usage and the demand for multi-touch, the capacitive touch technology inputting by fingers has become the mainstream of current electronic products.
A structure of a capacitive touch panel is a substrate on which transparent electrode patterns are coated. When a finger is close to or touches the touch panel, coupling capacitance is formed between the finger and the transparent electrode patterns because the finger is a conductor and has equivalent capacitance. Meanwhile, the capacitance of the electrode pattern positioned at a touch point on the touch panel will change, thus making the voltage or the current in the electrode change. Then by comparing a voltage difference between the electrode and the adjacent electrodes, the position of the touch point can thus be calculated.
However, although the touch input by the fingers is convenient, it is obviously difficult to achieve the following requirements: depicting lines with various thicknesses on the touchscreen, or touch recognition for fine locations by using the fingers. Therefore, in order to increase the accuracy of the touch input, a solution of using a stylus pen has been proposed. However, the input principle of a conventional capacitive stylus pen is mostly by disposing conductive plastic or conductive rubber on one end of a metal tube of the pen. Although it can achieve a more accurate input than the finger input, the capacitive stylus pen also can not depict the lines with the various thicknesses on the screen corresponding to force that exerts to the pen, the shortcoming of the usage still existing.
Accordingly, in order to represent the line with the various thicknesses on the screen, an active stylus pen that adopts Bluetooth or other wireless communication module to communicate with a tablet computer was suggested for achieving the above purpose. However, the establishment of the wireless communication will waste the active stylus pen and the tablet computer more power, and it is a disadvantage to the using time for both.